1. Field of the Invention
The present invention relates to an ophthalmologic apparatus that can perform observation, photographing, and capturing of image data of a clear retinal image with high magnification by adding an aberration compensation function that corrects wavefront aberration.
2. Description of Related Art
Conventionally, a retinal camera is known that performs observation and photographing of a retina by imaging the retina based on the reflected luminous flux from the illuminated retina. Howeyer, because the reflected luminous flux of the retina passes through an ocular optical system formed by a cornea, a crystalline lens, a vitreous body and so on, due to the effects of aberration of the ocular optical system, the retinal camera of this kind has a problem of not being able to obtain an image of a retina with high resolution as well as a clear image of a retina having high magnification. Incidentally, the ocular optical system is far from an ideal optical element, possesses optical refractive properties which generate various aberrations such as myopia and astigmatism, and the wavefront due to the reflected luminous flux from the retina has distortions.
On the other hand, an apparatus is proposed to obtain a clear image of a retina, having high magnification provided with an aberration measurement part which measures optical aberration of an eye and an aberration compensation part such as a deformable mirror for compensating the distortions of the wavefront of the reflected luminous flux caused by the optical aberration of the eye based on the signals from the aberration measurement part (refer to JP 2005-221579A).
Howeyer, since it is difficult to broaden the compensation range of a deformable mirror on the apparatus that uses the deformable mirror to compensate the aberration, the spherical diopter and the astigmatism diopter of the eye are compensated by adjusting an astigmatism compensation lens and a focusing lens disposed in a photographing system before photographing. The deformable mirror thereby compensates the remaining part of the compensation and higher-order aberration component. Hereby, the stroke of the focusing lens is quite large because it corresponds to hyperopia and myopia.
By the way, this deformable mirror generates a high-order aberration component by deforming a membrane as a reflective mirror into a desired shape. Since the membrane is deformed with only the electrostatic force by applying desired voltages to the electrodes disposed to face the membrane, it is inevitable that an infinitesimal spherical diopter is newly generated due to the deformation.
In order to solve this problem, it is thought that further compensation and adjustment by the focusing lens are required. Howeyer, since it is problematic that the accuracy and responsiveness will be low by the adjustment of the focusing lens, as a matter of practice, the compensation and the adjustment by the focusing lens can not be made. Consequently, the conventional technologies cannot perform high speed aberration compensation in correspondence to the infinitesimal spherical diopter newly generated by the deformable mirror, and it is problematic that the aberration by the infinitesimal spherical diopter will remain.